The invention relates to a method for determining the triggering sensitivity of an automatic braking process for a motor vehicle, dependent on the driving behavior of an individual driver.
An automatic braking process of the generic type is disclosed, for example, in German patent document DE 40 28 290 C1, in which automatic braking in a motor vehicle is triggered whenever the actuation speed of the brake pedal exceeds a prescribed threshold value. In automatic braking, brake pressure is generated which is greater than a brake pressure corresponding to the position of the brake pedal.
In the non-prepublished Patent Application DE-P. 43 25 940.5 the triggering sensitivity of the automatic braking process is determined by the speed of the vehicle and the position of the brake pedal. According to this disclosure, it is possible to match the triggering of the automatic braking process to the vehicle in itself by suitably selecting the threshold value, and to the current driving state--speed of the vehicle and position of the brake pedal. However, because triggering of the system is not adapted to the behavior of the individual driver, in the case of drivers who actuate the brake pedal only hesitantly, automatic braking may not be triggered in a situation in which triggering would actually be desirable. On the other hand, in the case of drivers who actuate the brake pedal violently even in a normal driving mode, automatic braking may be- triggered unnecessarily, in driving situations in which it is not desired.
It has been proposed, therefore, to provide a control element which can be actuated by the driver to adjust the triggering sensitivity of the automatic braking process within a specific range. The actuation of such a control element by the drivers of vehicles is not, however, absolutely reliable. Moreover, it is difficult for drivers to estimate or determine themselves the triggering sensitivity which is suitable for them.
The object of the invention is to improve the automatic braking process on which the generic type is based, with automatic adaptation of the triggering sensitivity of the system to the behavior of the driver.
This object is achieved by the automatic braking process according to the invention, in which a prescribed fixed threshold value Sf of the actuation speed of the brake pedal which triggers automatic braking is multiplied by a driver-dependent factor F, which is determined after each braking process as a function of the actuation speed and pedal travel of the brake pedal, in order to generate a driver-dependent threshold value Seff for triggering automatic braking. Thus, on the one hand, continuous adaptation to the driving behavior of the driver is ensured, while on the other hand, sufficient damping is ensured by taking into account all previous braking operations since the last resetting of the factor to an initial value. One simple way of detecting whether a braking process has been terminated consists, for example, in monitoring the switched position of the brake light switch.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.